You can view your purchase history by following these steps:

On your mobile device (iPhone/iPad):
  • Go to Settings
  • Tap on your Apple ID, at the top
  • Tap Media & Purchases, then tap View Account
  • In the Account window, tap Purchase history
On your computer:
  • Open iTunes on your computer
  • Click "Account" and log in (or confirm the email address)
  • Click "View my account..."
  • Scroll down to "Purchase History" and click "See All"